- ISBN: 0807554510, 9780807554517
- Page count: 121
- Published: 1998
- Format: Paperback
- Publisher: Albert Whitman & Company
- Author: Gertrude Chandler Warner
It's the Alden children's first trip to London, and it seems that someone is following them. Then Benny and Henry's room is ransacked and a beautiful broach with the initials HRH is found in Benny's backpack.